While we can't personally make the subway run more efficiently, we can figure out how to make your subway experience as cost-effective as possible. And with the MTA recently raising subway fares again, now's a good time to look at the new MetroCard math that comes with the new fare structure.

The 30-day MetroCard has increased from \$121 to \$127, while the 7-day has gone from \$32 to \$33, and the fare purchase bonuses have been eliminated. The one upside is that the fares got a lot simpler—you no longer have to divide e=mc2 by the negative square root of pi in order to figure out how much money to put on your card, and you won't be left with a frustrating \$1.19 bonus anymore. Now the only decision to make is whether to buy a 30-day MetroCard, a 7-day MetroCard, or individual swipes.

(Jen Carlson / Gothamist)

Let's break the options down: The 30-day MetroCard's cost of \$127 is the equivalent of ~46.2 single-swipes, so if you only ride the subway 46 times in 30 days, then single swipes are a better deal, but if you ride 47 times, you'll want to go with the 30-day card. To figure out if you're riding 47 times in 30 days, you'll need to consider a few things:

• If you use your MetroCard to commute to work and buy it on a Saturday, only 20 of the next 30 days will be business days, which probably means you'll be using it less. If you buy it Monday through Thursday you'll have the card for 22 business days. Unfortunately, once the card runs out, you'll have to buy a new one on whatever day that occurred. So if you plan to be buying a 30-day MetroCard for several months in a row, then buy the first card on a Monday so that you postpone having to buy it on a Saturday for as long as possible.
• Note how many major holidays you get off that fall within the 30 day period. For example, between December 24th and January 23rd there are three, which could potentially make for six fewer commutes. The 30-day MetroCard would probably not be a good deal during such a period.
• If you're not using your MetroCard at least 1 or 2 times per week outside of your commute on average, then the 30-day MetroCard is not for you.
• And now, a twist: the names "30-day MetroCard" and "7-day MetroCard" are not always accurate. More often than not, they are 6.5 day and 29.5 day MetroCards. If you buy a 7-day MetroCard and first use it at 11:59 p.m. Sunday, it does NOT expire at 11:59 p.m. the following Sunday, but rather at midnight—that’s 6 days and 1 minute after you first used it! Therefore you most definitely do not want to first use your 7-day/30-day MetroCards at night, especially after work on your 2nd ride of the day. You’ll want to first use your new card as early in the day as possible before you’ve taken any rides.

About that 7-day MetroCard—it is probably only worth considering this option if you are a tourist or doing a city-wide scavenger hunt. Fortunately, the math here is easy: the value of a 7-day MetroCard is exactly 12 rides, so you're only saving money if you're using the card 13 times during those 7 days. This is why the 7-day is so not applicable as a commuter card since 13 rides represent 6.5 commutes in 7 days. It'd only be worth it if you worked 7 days a week, but even then the 30-day would probably be a better deal unless the job was very short-term.

To recap: Commuters should buy the 30-day when riding 47 times per month, which is more likely to happen if you buy it in the morning, on a Monday, not during holiday season, and when you'll be riding on the weekends occasionally.

Correction: This article previously stated that the 7-day and 30-day MetroCard clock starts ticking upon purchase, but it starts at your first swipe.